Method of forming u-shaped clips of noncircular cross section



Aug.1"8," 1970 K.'A. 'KLE- 1 3,525,096

METHODOF FORMING U-SHAPED CLIPS 0F MONCIRCULAR CROSS SECTIO-N Filed March 19. 1969 '42 INVENTOR.

K4EL A. KLENZ United States Patent US. Cl. 14082 3 Claims ABSTRACT OF THE DISCLOSURE A wire clip of noncircular cross section is formed from a length of wire of conventional circular cross section by. rolling the wire to the desired noncircular shape while the same is being fed to the cutting and forming means.

This invention relates to a method of forming U-shaped clips of the type as shown in US. Pat. No. 3,400,433. This type of clip is employed for tying flexible containers such as bags, sausage casings and the like and, as pointed out in the referenced patent, certain advantages accrue from forming the U-shaped clip from wire which does not have a circular cross section but which presents a, flat face directed toward the article to be sealed. Although the particular cross section shown in the above noted patent will be used as an example in this disclosure it will be apparent that the present invention is applicable to any clip forming operation regardless of the particular noncircular cross section employed.

In manufacturing clips of the subject type the cus tomary procedure is for the manufacturer to purchase reels of wire from a wire supplier. In some instances thewire may be formed to a particular cross sectoin to meet the users specification but, in any event, the usual procedure is for the manufacturer to make the Wire to the desired shape by drawing the same through a die in a manner that is well known. One of the results of such a drawing process is that the wire develops a twist which makes it unwieldly to handle. However, if the wire is of circular cross section there is no particular orientation of the same required relative to its cross section. When a special cross section is desired such as the one shown in the cited patent the inherent tendency for the drawn Wire to twist creates many problems, the greatest one being that of orienting the wire with the noncircular cross section in a predetermined position relative to the clip forming means so that all clips are identical. Another problem is that the twisted wire is more likely to be damaged in handling. Furthermore, the required orientation requires special equipment which is unnecessary in the case of circular wire.

The main object of the present invention is the provision of a method for forming clips from wire of noncircular cross section and which method obviates the disadvantages of prior art methods presently available.

Another object of the invention is the provision of a method of forming U-shaped clips of noncircular cross section which permits the use of a compact arrangement of equipment to perform the step of shaping the wire to the noncircular cross section.

Another object of the invention is the provision of a method for forming U-shaped clips of noncircular cross section which results in a considerable saving in expense over the prior art method of purchasing the wire from a wire manufacturer to the users specification.

Still another object of the invention is the provision of a method of forming U-shaped clips from wire of noncircular cross section which has the advantage of per- "ice mitting the provision of an improved product with an extremely gOOd surface finish.

Other objects and advantages will be apparent from the following specification and from the drawings:

FIG. 1 is a side elevation of a clip forming press showllg the wire feeding and shaping means at one side there- 0 1 FIG. 2 is a horizontal section taken in the plane indicated by lines 22 of FIG. 1; and

FIG. 3 is a greatly enlarged fragmentary cross section of the peripheries of the wire forming rolls as taken in a plane indicated by lines 3-3 of FIG. 1.

The present method of forming U-shaped clips from a length of wire, whether the wire be of circular or noncircular cross section, is to feed the wire intermittently to a press provided with a wire cutting punch which cuts off a short length of the wire and, in one operation, bends the cut portion around an anvil to form the U-shaped clip.

Such a press is shown in FIG. 1 and, in general, includes a ram 2 at the lower end of the connecting rod 3 which is oscillatably mounted at its upper end on an eccentric portion of main shaft 4 which is provided with a flywheel (not shown) driven by any suitable source of power.

Secured to ram 2 is an upper die shoe 8 which is vertically slidable along a pair of vertically extending posts 9 and which has secured thereto a downwardly extending punch 10. A lower die shoe 12 is fixed to the base 13 of the press and fixedly'secured to said die shoe 12 is a clip forming rail 15 which is provided with a curved upper edge around which the wire is bent to form the U-shaped clip. Said rail extends horizontally outwardly from die shoe 12 and the completed clips 16 are fed along the length of said rail as shown in FIG. 2 to the clip packaging operation.

In the particular arrangement shown in FIGS. 1 and 2, two wires 20 and 21 are simultaneously fed toward the press from the lefthand side thereof and two wires 22 and 23 are fed by similar apparatus from the righthand side. Only one complete side is shown in the drawings. However, from FIG. 2 it will be apparent that the wires are staggered so that upon one reciprocation of the punch four wires are cut and four clips formed simultaneously.

The wires are fed to the punch through dies 24 in an upstanding portion 25 of a cutoff block generally designated 26. The upper surface of the cutoff block is formed with grooves 27, 28 for receiving the wires 20, 21 respectively prior to their passage through dies 24. By a means which will be described later on the wire is intermittently fed on each cycle a distance substantially equal to the spacing between the upstanding portions 25 of the two cutoff blocks so that as the punch 10 is urged downwardly from its upper position of FIG. 1 the four wires 20 to 23 are cut. Upon further downward movement of the punch 10 the ends of the cut wires are bent around the top of rail 13 by a recessed portion 30 at the lower end of punch 10. The final step in the clip forming operation is performed when the bottom of the recess 30 engages a stripper plate 31 and forces the same against the crown of the formed clip thereby setting the bent clip to an almost perfect U-shape. The stripper plate 31 is formed as shown in FIG. 2 and is yieldably supported on three upstanding studs 32 on die shoe 12. The stripper plate 31 is urged to its upper position by compression springs 33. It will be understood that the stripper plate 31 also functions to prevent the punch 10 from dragging the clips upwardly on its return stroke.

Upon each cycle of the mechanism a clip ejector 35 connected by a linkage to the upper and lower die shoes is translated along the length of rail 15 thereby ejecting the clips from the rail forming station and moving them with the already formed clips along the length of rail 15.

The above described structure is conventional and no claim is made thereto except in combination with the method herein claimed.

The wires 20, 21 are initially reeled around drums 40 which are rotatably supported on rollers to permit the wires to be fed oi the drums upon the imposition of a slight tension. The wires 20, 21 as they come from drums 40 are circular in cross section and are first passed between a group of grooved rollers 41 which are simply for the purpose of holding the wire so that it is fed along a predetermined path toward the forming rolls 42, 43. These rolls 42, 43 are keyed to upper and lower shafts 44, 45. Lower shaft 45 is rotatably supported in a pair of lower supports 46, 47 which in turn are secured to the lower die shoe 12. Upper shaft 44 is rotatably supported on a pair of relatively heavy blocks 48, 49 secured to supports 46, 47 respectively.

On one side of the apparatus each shaft 44, 45 is provided with an overrunning clutch 50 which is designed to permit free rotation in one direction and to prevent any rotation in the reverse direction. The lower shaft 45 is provided with a crank arm 52 which is pivotally connected at its outer end to a generally vertically extending connecting rod 53 which in turn is pivotally connected at its upper end to an eccentric 54 carried by an extension 55 of main shaft 4 of press 1. By this structure, upon each rotation of main shaft 4, representing a cycle, shaft 45 is oscillated a predetermined number of degrees. This oscillation is transferred through spur gears 58 to the upper shaft 44 so that both shafts undergo the same degree of turn upon each cycle. The overrunning clutches 50 permit rotation of shafts 44, 45 only in the feeding direction.

As best seen in FIG. 3 the upper form roll 42 is provided on its periphery with a relatively deep groove 60 which is adapted to receive the wire 20 therein. The lower roller 43 is provided on its periphery with a radially outwardly projecting annular enlargement 61 which fits with in the outer portion of groove 60. Only one pair of wire forming elements are shown in FIG. 3. Aside from the above described structure the peripheries of two formed rollers are plain and are in engagement along a line of contact 62. The bottom of groove 60 is formed to a shape generally complementarily to the desired cross section of the wire which, in this case, is generally trapezoidal.

It will be understood that the force exerted on the wire by rollers 42, 43 is considerable and not only shapes the round wire to the desired cross section but imparts sufficient frictional load on the wire to feed the same toward the press 1. Thus only rolls 42, 43 contribute to feeding the wire.

Interposed between the form rolls 42, 43 and the press 1 are a second group of rollers 65 which are formed on their peripheries with grooves that are complementary relative to the new cross section of the wire and which guide the wire through the grooves 27, 28 in the cutoff block 26 so that the wire remains properly oriented as it approaches the cutting step. The dies 24 formed in the upright portions 25 of the cutoff block 26 may have the same cross sectional shape as the new cross section of the wire so that the wire is properly oriented during the cuttlng and bending steps carried out by press 1.

Not only does the above described method of rolling the wire immediately prior to the cutting and forming steps obviate the difiiculty of orienting a preformed wire but the rolling of the wire by form rolls 42, 43 results 1n a drawing effect which polishes the wire as the area of the wire is reduced. A clean burnished surface of the wire therefore results immediately prior to the clip formmg step so that the finished clips may be packaged before exposure to the atmosphere adversely affects the surface.

The combination of the wire shaping operation and the were feeding step naturally represents a saving in power since the same source is employed for both.

I claim:

1. The method of making a U-shaped clip of noncircular cross section comprising the steps of:

providing a length of wire,

feeding said wire lengthwise to a wire cutting and clip forming means,

shaping said wire to such noncircular cross section at saig feeding step and during said feeding movement, an

thereafter cutting a section of said length of wire and forming it to a U-shaped clip.

2. The method of claim 1 wherein the shaping of the wire is performed by rolls.

. 3. The method of claim 2 wherein said rolls are driven in opposite directions and constitute the feeding means to said cutting and forming means.

References Cited UNITED STATES PATENTS 2,457,132 12/ 1948 Delaney 72-206 3,073,355 l/1963 Grinnell -82 3,112,775 12/1963 Garland l40l 3,184,943 5/1965 Ware 72-406 3,456,474 7/1969 McClellan et al. 72-199 LOWELL A. LARSON, Primary Examiner U.S. Cl. X.R. 72--203, 206 

